Solver "xpress" is based on FICO XPRESS, a solver for linear and quadratic programming problems involving continuous or integer variables by FICO http://www.fico.com/xpress Contact FICO for details on getting the XPRESS libraries and header files. Source file xpress.c is an AMPL driver for XPRESS. Files makefile.u and makefile.vc are sample makefiles for Linux or Unix systems and for Microsoft Visual C++, respectively. Copy one of them to "makefile" and edit the latter to have assignments to XPRESSDIR, S, CFLAGS, etc., that are suitable for your system. For a summary of using solver "xpress", execute xpress '-?' or xpress -? (depending on the syntax required by your shell). More details appear in README.xpress.